Vertebral fixation, also known as spinal fixation, is a neurosurgical procedure, in which two or more vertebrae are anchored to each other through a vertebral fixation device. It is an aim of such a neurosurgical procedure to reduce vertebral mobility and thus avoid possible damage to the spinal cord and/or the spinal roots. Indications for such a procedure are, amongst others, degenerative disk disease, spondylolisthesis, fracture, dislocation, spinal stenosis, fracture with instability, occipito-cervical dislocation, tumors and a revision of previous cervical spine surgery.
Common devices used to achieve vertebral fixation comprise permanent rigid or semi-rigid prostheses made of titanium. Known devices may include rods, plates, screws and various combinations thereof.
The medical community currently uses several different techniques for stabilizing the posterior region of the spine. The most radical of these techniques is spinal fusion. In recent years, spinal surgeons have begun to rely more heavily on mechanical implants which provide increased stability without so severely limiting the recipient's range of motion. A number of devices have been developed that allow the recipients an almost natural range of motion while still providing support. However, in many cases, the support offered by such devices is insufficient, leaving the physician with few other choices than spinal fusion.
A known device used to achieve vertebral fixation is shown exemplarily in FIG. 1. In FIG. 1, three vertebrae 20 are anchored to each other through a system comprising six spinal fixation devices 110. Two devices 110 are attached to each vertebra to be anchored. Each device 110 is attached to a respective vertebra by means of a screw 140. The devices 110 attached to different vertebrae 20 are coupled to each other via a connecting rod 130.
FIG. 2 shows a top view of a vertebra to serve as a reference for the following description. In FIG. 2, the different portions of the vertebra are identified. FIG. 3 shows a top view of a vertebra 20 similar to FIG. 2. In FIG. 3, however, two devices 110 have been attached to the vertebra 20. The devices 110 are attached to the vertebra 20 by means of a respective screw 140, which runs through the pedicle and the body of the vertebra 20. In common techniques for spinal fixation, usually a tool, generally indicated by reference numeral 150 in FIG. 3, is used to fix the screw 140 to the vertebra 20.
FIG. 4 shows a perspective view of a portion of a known spinal fixation system comprising two devices 110. The devices 110 are attached to different vertebrae 20 by means of a respective screw 140. Moreover, a rod 130 is connected between the devices 110 to anchor the vertebrae 20 to each other.
U.S. Pat. No. 8,162,946 B2 to Bacelli et al. discloses a surgical system for stabilizing a portion of a spine. The system comprises a spinal rod, an implant and an instrument. The instrument comprises a shaft, a moving part and a holder. The implant comprises a flexible tie and a bearing for bearing against the rod.
Moreover, U.S. Pat. No. 8,430,918 B2 to Bacelli et al. discloses a vertebral fixing system suitable for being mounted on a vertebra of the spine for connecting it to a rod. The system includes a connecting part suitable for being connected to the rod, a flexible ligature of elongated shape having two free ends suitable for connecting together the connecting part and at least a portion of a vertebra or a rib, and an adjustable locking member mounted on the connecting part.
In addition, US patent application No. 2009/0248077 A1 to Johns discloses a spine stabilization for the prophylactic treatment of adjacent level disease. A first vertebral level may be fused by advancing a pedicle screw in the first and second vertebra and coupling the bone screws to a rigid portion of a rod. A conformable ligature may be passed around a non-pedicle portion of a third vertebra and coupled to a dynamic portion of the rod using a blocking body.
However, known devices are usually difficult to attach to a vertebra and have the risk of causing damage to the spine.
It was therefore an objective of the present disclosure to provide a device that offers additional support to limit the compression on affected vertebrae while still offering a wide range of motion. It was a further objective to minimize the risk of damaging the spinal cord and the spinal roots when mounting the device to a vertebra during a surgical procedure. It was a further objective to provide a device that may easily be attached to a vertebra, and that may preferably be applied by the surgeon without requiring assistance to handle the device during the attachment process. It is a further objective of the present disclosure to allow a correction of the position of the implant after having attached the device to the vertebra.